The proposed studies are designed to examine the role of glutathione-conjugation in the detoxification of hydrophobic carcinogenic electrophiles in intact cells. We propose to use as experimental systems cells in established monolayer culture such as BHK21/C13, 3T3/BALB, V79, RAG, Chang, A549, H-4-II-E and subclones of the H-4-II-E cells which differ in the expression of liver-secific functions. The cell lines are chosen on the basis of their particular capacity for activation by the cytochromr P-450/P448-dependent monoxygenases, their level of reduced glutathone (GSH) and their activities of GSH S-transferases which are known from previous studies. Benzo(a)pyrene (BaP) and its metabolites will serve as model compounds. Attention will be focussed on the intracellular trapping of the BaP 7,8-oxide and the secondary oxidation product 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro-BaP by conjugation with GSH. To modulate the capacity for GSH-conjugation in the monolayer cells, the levels of the GSH will be suppressed by brief treatment with diethylmaleate. At various SH levels we will examine the cellular response to externally and internally formed metabolites of 3H-BaP and 3H-7,8-dihydroxy-7,8-dihydro-Bap by analysing the following parameters: a) formation of GSH-conjugates and other inactivation products, b) the degree of binding of reactive metabolites to DNA and the nature of the adducts, c) the appearance of alkaline-labile sites in the DNA, and d) the appearances of mutant cells. The studies should provide some insight into the effectiveness of GSH-conjugation and other inactivation products, b) the degree of binding of reactive metabolites to DNA and the nature of the adducts, c) the appearance of alkaline-labile sites in the DNA, and d) the appearance of mutant cells. The studies should provide some insight into the effectiveness of GSH-conjugation as a defense mechanism against hydrophobic carcinogens and may aid in evaluating the human risk to substance capable of reducing the levels of GSH or GSH S-transferases.